Bending machine having a bending head that is movable about a stationary bending shank

ABSTRACT

The machine for cambering, shaping, bending or curving a bar along a bending axis includes an arm, a bending shank supported by the arm, a bending head including a bending lug that is rotatable relative to the bending axis, and a feeding station for moving the bar along an axis of travel and across the bending shank. The bending head also includes: a first connecting rod supporting the bending lug and having a head, a second connecting rod having a head, the heads being coupled so as to rotate relative to a hinge axis perpendicular to the axis of travel, a first driver for translating a leg of the first connecting rod along an axis parallel to the axis of travel, and a second driver for translating a leg the second connecting rod along an axis parallel to the axis of travel.

RELATED U.S. APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO MICROFICHE APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a machine for cambering, shaping, bending or curving a bar along a bending axis, said machine comprising

-   -   an arm,     -   a bending shank carried by the arm,     -   a bending head comprising a rotatable bending lug that is         rotatable relative to the bending axis, and     -   a feeding station located upstream from the bending shank for         moving the bar along an axis of travel and across the bending         shank.

2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.

Such a machine is known namely from FR 2806943, which describes a machine in which the bending head is movable in translation along an axis perpendicular to the axis of travel of the bar, the bending shank carried by the arm is movable in translation along the axis of travel relative to the frame and, hence, relative to the bending head. This machine permits to make a large number of forms, namely loops, and shapes of varied diameters. However, the rigidity of the bending shank is altered in that the shank is carried by a movable support and the mechanical backlashes inherent to the guiding of the telescopic shank.

In addition, the arrangement of the movable shank obliges, in the majority of the bending sequences using this arrangement, to move the bar in the same proportion as the shank. This results into alternating movements in addition to those required only by the bending, and therefore a loss of accuracy in the axial positioning of the bar.

On the other hand, the axial displacement of the shank requires to use a telescopic bar guiding tube having limited guiding qualities.

SUMMARY OF THE INVENTION

The invention provides a new machine, which does not have the drawbacks of a machine as described above. More specifically, the invention provides a machine for cambering, shaping, bending or curving a bar along a bending axis, said machine comprising

-   -   an arm,     -   a bending shank carried by the arm,     -   a bending head comprising a rotatable bending lug that is         rotatable relative to the bending axis, and     -   a feeding station located upstream of the bending shank for         moving the bar along an axis of travel and across the bending         shank.

The machine according to the invention is furthermore characterized in that the bending head also comprises:

-   -   a first connecting rod carrying the bending lug,     -   a second connecting rod, a head of which is coupled to a head of         the first connecting rod so as to rotate relative to a hinge         axis perpendicular to the axis of travel,     -   a first driving means for translating a leg (82) of the first         connecting rod along an axis parallel to the axis of travel, and         a second driving means for translating a leg of the second         connecting rod along an axis parallel to the axis of travel

Thus, in a machine according to the invention, the bending head is driven in movement by the combination of two connecting rods, the leg of which is translated along an axis parallel to the axis of travel of the wire. A suitable control means for driving in translation of the leg of the connecting rods permits a bending movement of the bending lug relative to the frame and the bending shank, in translation along the (e.g. horizontal) axis of travel and/or in translation along a (e.g. vertical) axis perpendicular to the axis of travel, as will be better seen below. It is thus possible to make at least the same shapes as with a prior-art machine described above. But an appropriate control of the means for driving in translation the leg of the connecting rods also permits displacements of the bending lug according to other trajectories in a bending plane passing through the axis of travel, so that it is possible to make a large number of shapes.

In a machine according to the invention, the bending shank can be fixed relative to the arm, for the translational motion of the shank with respect to the bending head can be performed by means of an appropriate control of the means for driving the leg of the connecting rods in translation. Since the displacement of the bending head is faster than the displacement of the bending shank, the speed of execution of the bending is higher. In addition, in a machine according to the invention, the mechanical backlashes namely of the fixed bending shank are limited. The quality of the parts being produced is improved.

Since the heads of the two connecting rods are connected to each other, and the bending lug is carried by one of the connecting rods, the control in translation of the legs of the two connecting rods is sufficient for causing the bending head (the connecting rods, the bending lug) to move. A specific control of the lateral motion of the bending head is not necessary.

The arm may be rotationally mounted relative to the frame along the axis of travel. This permits, before carrying out a bending, to orient the bending shank relative to the bending head.

The bending head can also comprise a cambering roller rotationally mounted relative to its axis (i.e. along an axis of the roller) parallel to the bending axis. The roller permits to make specific forms, namely loops and bends of more than 180°.

The bending lug can also be freely rotating about its axis (i.e. along an axis of the bending lug) parallel to the axis of bending, which considerably limits the friction forces of the bending lug on the bar to be bent.

According to a variant, the bending lug, and roller if there is one, is fixed to the bending head, for example on the first connecting rod, rotationally relative to the bending head. According to another variant, the bending head comprises a tool detachably mounted on the bending head; the tool comprises a supporting part, on which the bending lug (and the roller if there is one) is mounted; the bending head comprises means for driving the supporting part for the tool in rotation according to the bending axis. In other words, the bending lug, and the roller if there is one, are mounted on a supporting part, the unit comprised of the supporting part, the bending lug and the roller forming a tool; since the tool is detachably mounted on the bending head, it is very easy to replace it in order to perform bends of different shapes and/or diameters, while maintaining the same means for causing the bending head to move.

In one embodiment, the tool may comprise a fixing pin extending from a first face of the supporting part of the tool; the bending lug and eventually the roller extend from a second face of the supporting part of the tool, and the bending head comprises in addition:

-   -   a jaw adapted for receiving the fastening pin and for         immobilizing the fastening pin in rotation and in translation,         and     -   means for driving the jaw in rotation about the bending axis.

The pin of the tool and the jaw of the bending head form together a means for detachably securing the tool on the bending head. When the tool is mounted on the bending head, the axis of the jaw, the axis of the pin and the bending axis coincide. The jaw is for example fastened to the head of the first connecting rod.

The axis of the bending lug or the axis of the cambering roller may coincide with the bending axis for specific bends.

Depending on the external shape of the bar to be bent, the external side surface of the bending lug and/or the cambering roller may have a surface of revolution about the axis of the bending lug or the axis of the cambering roller, e.g. a cylindrical surface, or a surface having the shape of a portion of a tube closed on itself (shape of a cut tube closed on itself, shape of revolution obtained from an arc of a circle). Such a surface is well-suited for permitting the rotation of the bending lug of the roller on itself as the bending lug or roller moves along the bar to be bent, which limits the friction forces.

According to a variant, the outer surface of the bending lug is locally, on a portion of said outer surface:

-   -   planar, in a plane parallel to the axis of the bending lug or         the axis of the cambering roller, or     -   cylindrical concave, along an axis perpendicular to the axis of         the bending lug or the axis of the cambering roller, a diameter         of the cylinder corresponding to the diameter of a bar to be         bent.

Such a surface is well-suited to match as well as possible the shape of a bar to be bent and permits to perform bends without the bending lug or cambering roller sliding on the bar to be bent.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood and further features and advantages of the invention will become clear from the following description of exemplary embodiments of a bending machine according to the invention. These examples are given in a non-restrictive way. The description should be read in conjunction with the attached drawings.

FIG. 1 a is a partial schematic view of a machine according to the invention, the tool being out of its recess.

FIG. 1 b is a kinematic diagram illustration of the elements of FIG. 1 a.

FIG. 2 a shows a schematic view of a tool comprising a bending lug.

FIG. 2 b shows a schematic view of a tool comprising a bending lug and a roller.

FIG. 2 c shows a schematic view of another tool comprising a bending lug and a roller.

FIGS. 3 a and 3 b show schematic views of the kinematics of a bending on the bending shank.

FIGS. 4 a and 4 b show schematic views of the kinematics of a bending on the bending axis.

FIGS. 5 a to 5 c show schematic views of the kinematics of an offset bending (5 a=position at the end of the second bend, 5 b=position at the start of the 3rd bend, 5 c=position at the end of the third bend).

FIGS. 6 a and 6 b show schematic views of the kinematics of the carrying out of two counter-bends in one operation.

FIGS. 7 a and 7 b show schematic views of the kinematics of a bend without sliding.

DETAILED DESCRIPTION OF THE DRAWINGS

In order to make the reading easier, in the description only the word “bar” has been used to refer more generally to a blank that can be a bar, a wire, a tube, a profile before bending.

Also for simplicity reasons, we have chosen to describe the embodiments and the movements of the elements of the machine according to the invention with respect to the horizontal plane of the figures, corresponding to the vertical plane of the upright machine, the words “top”, “bottom” are thus defined relative to the plane of the figures. But these embodiments are of course reproducible in all working planes.

Finally, the words “upstream” and “downstream” are defined as usual, along the bar to be bent and in the direction of travel of the bar.

DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

In the examples shown, a machine according to the invention includes:

-   -   an arm 10, rotatable about the axis of travel and fastened to a         static frame, not shown,     -   a bending shank 20 carried by the arm 10, and fixed relative to         the arm,     -   a bending head 50 to which is fastened a tool 70 rotatable         according to a bending axis,     -   a feeding station (not shown) located upstream of the bending         shank for moving a bar along an axis of travel and across the         bending shank.

The bending head also comprises:

-   -   a first connecting rod 80, a head 81 of which carries the tool         70     -   a second connecting rod 90, a head 91 of which is coupled to the         head 81 of the first connecting rod 80 in rotation relative to a         hinge axis A perpendicular to the axis of travel B and parallel         to the bending axis P.

The bending head also comprises a first driving means 30 for driving in translation a leg 82 of the first connecting rod along an axis parallel to the axis of travel, and a second driving means 40 for driving in translation the leg 92 of the second connecting rod 90 along an axis parallel to the axis of travel. The leg 82 of the first connecting rod 80 is freely rotating relative to the driving means 30 and can thus rotate freely about an axis parallel to the bending axis. Similarly, the leg 92 of the second connecting rod is freely rotating relative to the driving means 40 and can thus rotate freely about an axis parallel to the bending axis.

In the example namely of FIGS. 2 a, 2 b, 2 c, the tool 70 comprises a supporting part 71 comprising an fastening pin 74 extending from a first face of the supporting part 71 of the tool.

The bending head 50 comprises means for driving the tool in rotation according to the bending axis P. In the examples shown, the driving means comprises:

-   -   a jaw 60 adapted to receive the fastening pin 74 and to         immobilize the fastening pin, and     -   means (not shown) for driving the jaw in rotation about the         bending axis; the bending axis, the axis of the jaw and the axis         of the pin coincide when the tool is mounted in the jaw.

The bending axis P is the axis of the bending head about which the bending lug is likely to be driven in rotation.

Different tools permit to make different bends or curves on bars of different diameter and shape, depending namely on the shape and diameter of the bending lug, the presence or absence of a roller, the shape and the diameter of the roller, the position of the axis of the bending lug and/or of the axis of the roller relative to the bending axis, etc. A tool mounted on the bending head can be easily replaced by another one.

In the examples shown in FIGS. 2 a, 2 b, 2 c, the bending lug 72 extends from a second face of the supporting part and is mounted freely rotating relative to the axis D of the bending lug, parallel to the bending axis P.

In Example 2a, the tool also comprises a cambering roller extending parallel to the bending lug, from the second face of the supporting part along an axis G of the roller parallel to the bending axis P. The roller is here mounted freely rotating about its axis.

In the examples namely of FIGS. 2 b, 4 a, 4 b, the tool also comprises a cambering roller 73 extending parallel to the bending lug 72, from the second face of the supporting part along an axis G of the roller parallel to the bending axis P. The roller is here mounted freely rotating about its axis.

In the example namely of FIGS. 4 a, 4 b, 6 a, 6 b, the axis G of the roller is coincident with the bending axis P and the axis D of the bending lug is offset with respect to the bending axis P. In the example namely of FIGS. 8 a, 8 b, the axis of the roller and the axis of the bending lug are offset with respect to the bending axis.

In the example of FIGS. 3 a, 3 b, the outer side surface of the bending lug is a surface of revolution about the axis of the bending lug, more specifically a recessed surface forming a groove into which can be positioned a cylindrical bar to be bent. The bar is maintained perfectly laterally and cannot move in translation along the bending axis.

In the example of FIGS. 7 a, 7 b, the outer surface of the bending lug is locally cylindrical concave, along an axis perpendicular to the axis of the bending lug or the axis of the cambering roller, a diameter of the cylinder corresponding to the diameter a bar to be bent. It is thus perfectly adapted to rest on the surface of a tube for performing a bend without sliding.

The means for driving the bending lug in rotation relative to the bending axis and the means for driving in translation the ends 82, 92 of the connecting rods are controlled by digital control means, in other words by control software that can be parameterized by a user depending on the bends to be performed. The bending axis of the machine is a horizontal axis perpendicular to the longitudinal axis of the bar to be bent. The means driving in translation the ends 82, 92 of the connecting rods permit a precise positioning of the intersection of the bending axis of the machine in the vertical plane passing through the longitudinal axis of the bar to be bent. Then, the rotation of the bending lug along the axis of bending, eventually in combination with a simultaneous displacement of the bending axis, permits to perform the desired bending, as can be seen in the examples below.

Some feasible examples of bends with a machine according to the invention will now be described in connection with FIGS. 3 to 8. In the figures, the arrows indicate the movements made by the tool to perform a bending.

FIGS. 3 a, 3 b show the kinematics of a bending of a cylindrical bar on the bending shank. The tool being used comprises a bending pin, the axis of which is offset with respect to the bending axis. The bar is fed across the bending shank, and is immobilized in the bending shank. In the initial position (FIG. 3 a), the bending lug 72 is positioned under the bar, into contact with the bar. The bending axis is perpendicular to the axis of the bar and passes through the axis of the bar. In order to make the bend, the bending lug is driven in rotation about the bending axis, until its final position (FIG. 3 b). The shape of the bend is provided by the shape of the bending shank.

FIGS. 4 a, 4 b show the kinematics for making a bend on the bending axis. The tool comprises a roller, the axis of which is coincident with the bending axis, and a bending lug, the axis of which is offset with respect to the bending axis. The bar is moved across the bending shank and protrudes downstream of the bending shank by a sufficient length to form the bend without the bending head coming into contact with the bending shank. In the initial position (FIG. 4 a), the bending axis is positioned relative to the bar so that the roller and the bending lug are into contact with the bar to be bent, one being located above and the other one under the bar. Then, the bending lug is driven in rotation and slides or rolls on the end of the bar, which bends until the final position (FIG. 4 b). Since the bending head is sufficiently separated from the bending shank, the bending can range in the example shown as far as forming a closed loop.

FIGS. 5 a to 5 c show the kinematic for making several successive 90° bends along a cylindrical bar. The tool being used is the same as in the example of FIGS. 4 a, 4 b. In FIG. 5 a, the first bend (closest to the bending shank along the bar) is already made and the second bend, downstream of the first one has just been completed. The roller is positioned inside the second bend and the bending lug is positioned outside of the second bend, downstream of the roller. In order to make the third bend, the bending axis is first shifted in translation along an axis parallel to the axis of the bar in the bending shank until the position at which the bend has to be made (FIG. 5 b), then, the bending lug is driven in rotation to perform the bending (FIG. 5 c). In the example of FIGS. 5 a-5 c, a flat part having a rectangular cross-section has thus been made.

FIGS. 6 a, 6 b show the kinematics for simultaneously making two counter-bends, one on the bending shank, the other one around the roller. The tool being used is the same as in the example of FIGS. 4 a, 4 b. In the initial position, the bending axis and the bending lug are positioned such that the bending lug and the roller are positioned on either side of the bar to be bent and into contact with the bar. The bend is then made by moving the bending head (and thus the bending axis) along a curved path until its end position (FIG. 6 b), the bending lug being held stationary relative to the bending axis. It should be noted that, here, only the bending axis is moved during the bending phase. Unlike the previous examples, where only the bending lug was rotated relative to the bending axis during the bending phase, the bending axis (and thus the bending head) remains stationary.

FIGS. 7 a, 7 b show the kinematics for making a bend without sliding a cylindrical bar on the bending shank of the machine. The tool being used here comprises a bending lug, the axis of which is offset with respect to the bending axis. The roller is unnecessary in this example. In the initial position (FIG. 7 a), the bending lug is resting under the bar, so that the line perpendicular to the bending axis and passing through the axis of the bending lug is perpendicular to the bar to be bent. The bend is then made by moving in rotation the bending head and the bending axis, the bending lug being held stationary relative to the bending axis (FIG. 7 b). The bend is made, here, without sliding, i.e. the point of contact between the bar and the line perpendicular to the bending axis and passing through the axis of the bending lug is the same during the entire bending phase. It should be noted that, in this example, during the bending phase the bending lug is stationary, and namely does not rotate on itself, as such may be the case in the previous examples.

Of course, many other bends may be contemplated with a machine according to the invention, namely depending:

-   -   on the shape and the dimensions of the bending shank being used     -   on the shape and dimensions of the tool being used, with a         bending lug, and with or without roller     -   on the movement of the bending axis (the bending head) before         and/or during the bending phase, whereby the point of         intersection of the bending axis can describe any curve in the         vertical plane through a suitable control of the means for         driving in translation the second ends 82, 92 of the connecting         rods 80, 90,     -   on the rotary motion of the bending lug relative to the bending         axis through a suitable control of the means for driving in         rotation the bending lug.

LIST OF REFERENCE NUMERALS

-   10 arm -   20 bending shank carried by the arm -   30, 40 means for driving in translation a leg of a connecting rod     80, 90 -   50 bending head -   60 jaw of the bending head -   70 tool -   71 supporting part -   74 pin extending along the bending axis when the tool is mounted in     the jaw -   72 bending lug, rotary about an axis D parallel to the bending axis     P -   73 roller, rotary relative to an axis G parallel to the bending axis     P -   80, 90 connecting rods -   81, 82 head and leg of the connecting rod 80 -   91, 92 head and leg of the connecting rod 90 -   100 bar -   P bending axis -   B axis of travel -   G axis of the roller -   D axis of the bending lug -   A hinge axis of the two connecting rods 80, 90 

1. Machine for cambering, shaping, bending or curving a bar along a bending axis, said machine comprising: an arm, a bending shank carried by the arm, a bending head comprising a rotatable bending lug rotatable relative to the bending axis, and a feeding station located upstream from the bending shank for moving the bar along an axis of travel and across the bending shank, wherein said bending head comprises: a first connecting rod carrying the bending lug, a second connecting rod having a head coupled to a head of the first connecting rod so as to rotate relative to a hinge axis perpendicular to the axis of travel, a first drive means driving in translation a leg of the first connecting rod along an axis parallel to the axis of travel, and a second drive means for driving in translation a leg of the second connecting rod along an axis parallel to the axis of travel.
 2. Machine according to claim 1, wherein the arm is rotationally mounted along the axis of travel relative to a frame of the machine.
 3. Machine according to claim 1, wherein the bending head also comprises a cambering roller rotationally mounted relative to an axis of the roller parallel to the bending axis.
 4. Machine according to claim 1, wherein the bending lug is freely rotating about an axis of the bending lug parallel to the bending axis.
 5. Machine according to claim 1, wherein the bending head also comprises a tool detachably mounted on the bending head, the tool comprising a supporting part on which the bending lug is mounted, the bending head comprising a means for driving in rotation the supporting part of the tool according to the bending axis.
 6. Machine according to claim 5, wherein the bending head also comprises a cambering roller rotationally mounted relative to an axis of the roller parallel to the bending axis, and wherein the cambering roller is mounted on the supporting part of the tool.
 7. Machine according to claim 5, wherein the tool comprises a fastening pin extending from a first face of the supporting part of the tool, the bending lug and eventually the roller extending from a second face of the supporting part of the tool, and wherein the bending head comprises: a jaw adapted to receive the fastening pin and to immobilize the fastening pin, and means for driving the jaw and the tool in rotation about an axis of the jaw forming the bending axis.
 8. Machine according to claim 3, wherein the axis of the bending lug or the axis of the cambering roller coincides with the bending axis.
 9. Machine according to one of the preceding claims claim 3, wherein the external side surface of the bending lug and/or the cambering roller is a surface of revolution about the axis of the bending lug or the axis of the cambering roller.
 10. Machine according to claim 1, wherein the outer surface of the bending lug is locally: planar, in a plane parallel to the axis of the bending lug or the axis of the cambering roller, or cylindrical concave, along an axis perpendicular to the axis of the bending lug or the axis of the cambering roller, a diameter of the cylinder corresponding to the diameter of a bar to be bent. 